1. Field of the Invention
The present invention relates to methods and apparatus for the continuous supply of reeled web material such as paper into a continuous converting machine.
2. Description of the Prior Art
Continuous web converting machines such as printing presses and cutter/slitters are generally constructed to draw material from a supply reel.
So as to expedite the transition from a depleted reel to a full reel, spider wheel turret mechanisms are used such as that disclosed by O. C. Roesen in his U.S. Pat. No. 2,320,658.
To level the inertial forces as a web is unreeled, it is known to use a closed circuit pulling belt bearing against a small arcuate portion of the active reel. The belt is independently driven thereby driving the active reel at a substantially constant surface velocity.
Due to the fact that the reel diameter diminishes as it is depleted of web, it is necessary to accommodate such dimension changes in a manner consistent with the constant surface velocity. Furthermore, in the case of extremely soft web reels such as creped paper and the like, it is necessary to provide a carefully controlled bearing force against the reel.
Normally, these opertional constraints are accommodated by the use of weighted or spring loaded dancer rolls in the pulling belt circuit. These devices maintain a constant belt tension notwithstanding geometric changes in the circuit.
When the dancer roll pulling belt system is used in combination with a spider wheel unwind stand, an unusually large change in circuit geometry must be accommodated due to the arcuate sweep of the spider wheel about a fixed spider wheel axis.
Consequently, the magnitude of machine length and volume to accommodate the increased dancer roll stroke is proportionately increased. In some instances, as in the case of Roesen patent disclosure, supra, the pulling belt unit of the machine is so large as to be positioned beyond the reel unwind stand from the converting machine, per se. This arrangement severely restricts operator accessibility of the unwind stand for loading and unloading.
Another limiting facet of the spider wheel unwind stand arrangement is that of web severance from the depleted reel after a splice from a full reel has been completed. It is difficult to adapt conventional web cutters due to the necessity for cutter structure to be positioned within the swept volume of the reel magazine.
It is an object of the present invention therefore, to provide a web tail severance method and apparatus suitable for use with unwind stands of the rotating turret or spider wheel type.